Major League Baseball MVP Ryan Braun reportedly tested positive for steroid use on Saturday, a shock for a game whose marquee players had largely overcome their collective reputation as a tainted bunch of juicers.

A Foolproof Method

Under the latest MLB drug testing policy, players are asked to pee in a cup randomly twice per season, and more during playoffs. While doing so, they are observed closely, explains Will Carroll in Sports Illustrated.

When a player is selected for random testing, he is taken to a "clean area" designated in each clubhouse. He is observed urinating in a provided sample cup, which is sealed and initialled. (Observed? Yes, that means what you think. The "full stream" must be visible from player to cup.) That sample is prepared and sent to MLB's designated lab.

The sample is then split in half. If the first half triggers suspicion, that usually means a higher than normal testosterone to epitestosterone ratio was detected. Both types of testosterone occur naturally, and in most men the ratio is 1:1, though it can fluctuate. If it's anything above 4:1, it's not a positive test, it just means they'll want to test the other half of the sample. We know that in Braun's case the suspicion was triggered, but we don't know for sure yet what the second half of his sample revealed.

The Rare Exception

If the other half does test positive (and the MLB keeps secret how exactly they do the second test though Carroll points out that carbon isotope ratios or chromatography are state of the art), the player is pretty much screwed. He can claim his trainer or his cat tricked him into taking an unknown substance—regardless of how it got there, it's a positive test. Even if it got there without the player's knowledge, it's not a "false positive." There is only one exception, Carroll explains:

MLB (and the NFL, among others) have a list of substances that are certified by the NSF. Known as the "blessed list," these substances can be taken with confidence that they would not be tainted. Any other supplement, such as the 6-OXO Extreme that caused a positive for Phillies reliever J.C. Romero, would provide the player no such defense.

Because the testing process is so closely controlled by the standards laid out by the World Anti-Doping Agency, the chances of an outlier or an incorrect reading are extremely unlikely. And it's also not like a dude, no matter how manly he may seem, will spontaneously start producing synthetic testosterone.

What Happens Now?

As of 2005, punishment for a positive test is harsh: a 50-game suspension. The second positive test gets you a 100-game suspension, and a third results in a lifetime suspension from MLB.

Whether that will be Braun's fate is still unclear since we don't know yet for sure if his second sample tested positive. And some reports say that Braun requested a second, separate test, which didn't test positive. But that doesn't really make sense until we know more about the second half of the sample from his first test. Lastly, that second test would have to have happened between two and four weeks after the first for it to accurately affirm or dismiss the first test.

It's super complicated, and a guilty doper can only hope to make it appear more complicated and confuse his formerly adoring fans. Or, maybe Braun is the innocent and honest dude he always appeared to be and is the victim of faulty testing. Maybe he has a really nuts enemy who injected him with drugs without his knowledge! Who knows?

We will all likely know in January when Braun faces his MLB hearing. And if you're wondering how many times a positive performance-enhancing drug test has been overturned in the past? That would be never.

Update: As Deadspin points out, while official appeals have not been overturned in the majors, some minor leaguers have won a reversal in the past. And there are also some cases wherein a finding will be dismissed during a meeting between the players union and league officials. Still, those cases are the exception far more than they are the rule. [Sports Illustrated, Boston Herald]